That's a very interesting web site. It is obvious that a lot more research has been done on the whole area than was available when the books were written. Both will though, I am sure, be well out of print by now.
However, despite the obvious hand working of the mine itself, there was at least one steam loco - a small Bagnall wing tank. Roy Link has made a model of it or of a very similar one (and no it isn't Excelsior I am thinking of).